Multilayer Laminated Film

Abstract

A multilayer laminated film whose use is particularly suitable for the packaging of food which must undergo a high-temperature thermal treatment after packaging has occurred at least partly, the film comprising at least two layers, of which at least one first layer is made of plastic material and is intended for heat-sealing and at least one second outer layer is made of a material selected among plastic material, metallic material, paper-like material or equivalents; each layer is coupled to the adjacent one by means of an interlayer made of adhesive material. The first heat-sealing layer is of the type with a low-density cavitated structure.

1 - 23 . (canceled) 
   
   
       24 . A multilayer laminated film of the type which comprises at least two layers, of which at least one first layer is made of plastic material and is intended for heat-sealing and at least one second outer layer is made of a material selected among plastic material, metallic material, paper-like material or equivalents, each layer being coupled to the adjacent one by means of an interlayer made of adhesive material, said multilayer laminated film being characterized in that said first heat-sealing layer is constituted by at least two sublayers, at least one of which is of the type with a cavitated structure. 
   
   
       25 . The multilayer laminated film of  claim 24 , wherein said first layer with cavitated structure is constituted by at least two sublayers, which are produced by means of a multilayer coextrusion process and are enriched during said coextrusion process with one or more inert additives which are incompatible with the polymeric matrix, said coextrusion process being followed by an operation for mono- or biaxially-oriented stretching of said first extruded layer. 
   
   
       26 . The multilayer laminated film of  claim 24 , wherein the process for producing said cavitated layer comprises, after the mono- or biaxial stretching step, an annealing step which is suitable to contain dimensional shrinkage at high temperatures. 
   
   
       27 . The multilayer laminated film of  claim 25 , wherein said inert additive is calcium carbonate or another equivalent additive. 
   
   
       28 . The multilayer laminated film of  claim 25 , wherein said inert additive is present in an inner sublayer of said at least two sublayers in an amount comprised between 1% and 50%. 
   
   
       29 . The multilayer laminated film of  claim 28 , wherein said inert additive is present in the inner sublayer in an amount equal to 30%. 
   
   
       30 . The multilayer laminated film of  claim 28 , wherein said inert additive is present in an outer sublayer of said at least two sublayers in an amount which is lower than 50%. 
   
   
       31 . The multilayer laminated film of  claim 30 , wherein said inert additive is present in the outer sublayer in an amount equal to 20%. 
   
   
       32 . The multilayer laminated film of  claim 30 , wherein the inner sublayer has a higher degree of cavitation with respect to said outer sublayer and a melting point which is lower than, or equal to, a melting point of the outer sublayer. 
   
   
       33 . The multilayer laminated film of  claim 24 , wherein the heat-sealing layer is constituted by an inner sublayer with a melting point between 140° C. and 150° C. and by an outer sublayer with a melting point between 150° C. and 165° C. 
   
   
       34 . The multilayer laminated film of  claim 24 , wherein the density of said first layer having a cavitated structure is comprised between 0.400 and 0.880 grams per cubic centimeter. 
   
   
       35 . The multilayer laminated film of  claim 24 , wherein the density of said first layer having a cavitated structure is 0.700 grams per cubic centimeter. 
   
   
       36 . The multilayer laminated film of  claim 35 , wherein said first layer, which is stretched mono- or biaxially, has a thickness comprised between 30 and 120 microns. 
   
   
       37 . The multilayer laminated film of  claim 36 , wherein said first layer, which is stretched mono- or biaxially, has a thickness of 70 microns. 
   
   
       38 . The multilayer laminated film of  claim 24 , wherein at least one of said sublayers which compose said first heat-sealing layer has heat-sealing properties. 
   
   
       39 . The multilayer laminated film of  claim 33 , wherein said first layer, which is coextruded and oriented, is constituted by two sublayers, each of which is made of a plastic material selected between polypropylene and polyethylene. 
   
   
       40 . The multilayer laminated film of  claim 39 , wherein said first layer, which is coextruded and oriented, is constituted by three sublayers, each of which is made of a plastic material selected between polypropylene and polyethylene. 
   
   
       41 . The multilayer laminated film of  claim 24 , wherein said second outer layer is made of a plastic material selected among oriented polyethylene terephthalate, oriented polypropylene or oriented polyamide. 
   
   
       42 . The multilayer laminated film of  claim 24 , comprising, interposed between said first layer and said second layer, a third layer made of metallic material or plastic material, which is joined to each of the adjacent first and second layers by means of an interlayer made of adhesive material. 
   
   
       43 . The multilayer laminated film of  claim 42 , wherein said third layer is made of aluminum. 
   
   
       44 . Use of a multilayer laminated film comprising at least two layers, of which at least one first layer, made of plastic material, is intended for heat-sealing, and at least one second outer layer, is made of a material selected among plastic material, metallic material, paper-like material or equivalents, in which each layer is coupled to the adjacent one by means of an interlayer made of adhesive material and wherein the heat-sealing layer is constituted by at least two sublayers, at least one of which is of the type with cavitated structure, for producing bags and other similar enclosures for packaging precooked ready-to-eat food which has to undergo, when already stored within one of said bags or the like, thermal processes such as pasteurization, sterilization and the like. 
   
   
       45 . The use of a multilayer laminated film of  claim 44 , wherein the first layer of said film, which has a cavitated structure, is constituted by at least two sublayers, which are produced by means of a multilayer coextrusion process and are enriched during said coextrusion process with one or more inert additives, said coextrusion process being followed by an operation for mono- or biaxial stretching of said first coextruded layer and by an annealing operation for containing dimensional shrinkage at high temperatures. 
   
   
       46 . Use of a multilayer laminated film comprising at least two layers, of which at least one first layer, made of plastic material, is intended for heat-sealing and at least one second outer layer, made of a material selected among plastic material, metallic material, paper-like material or equivalents, in which each layer is coupled to the adjacent one by means of an interlayer made of adhesive material and wherein the heat-sealing layer is constituted by at least two sublayers, at least one of which is of the type with cavitated structure, to produce bags and other similar enclosures with reduced resistance to linear tearing in a preferential direction for packaging precooked ready-to-eat food which must undergo, when already stored within one of said bags or the like, thermal processes such as pasteurization, sterilization and the like.